1. Field of the Invention
The present invention relates to a data distribution system, more particularly relates to a data distribution system suitable for distributing a large volume of data like movies and music to users from a data provider (content provider).
2. Description of the Related Art
As will be explained later by referring to the drawings, the following problems occur in the data distribution system comprised by a network, a router, a cache server, and a distribution server.
There are a plurality of routers in a network. Data is transferred to a target cache server while sequentially relayed by these routers. In this case, collision of the data may occur at an incoming port or an outgoing port of each router. Also, collision of data may occur also at the cache server on a receiver side.
In order to avoid such collision of data in advance, a buffer is provided in each router, the data is temporarily stored in this buffer, and the data is read out from the buffer at the optimum transmission timing of the data, that is, a timing where collision can be avoided.
However, a buffer does not have a capacity (buffer amount) large enough to hold a large volume of data such as a movie and music for a long time. For this reason, the data has to be discarded if the buffers receive a large volume of data.
If this happens, the related data is repeatedly retransmitted between the routers and the distribution server due to the discarding of the data. Such repeated retransmission of data wastes the resources of the network and in the end results in the problem of fall in the efficiency of operation of the network.